POS0428 EFFECTOR ACTIVITY OF CXCR3+ CD8 T CELL IS REGULATED BY GLUT1-MEDIATED METABOLIC REPROGRAMMING TOWARD GLYCOLYSIS AND INVOLVED IN SPONDYLOARTHRITIS PATHOGENESIS
Authors: ミ. コロヤス, M. Akiyama, T. Kaburaki, K. Yoshimoto, Y. Kaneko
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Although T cell metabolism has recently attracted attention as a key regulator of immune responses, the molecular mechanisms underlying the expression of effector functions in human T cells are still poorly understood. T cell metabolism is postulated to be involved in the development of autoimmune diseases by regulating the expression of its effector functions. <h3>Objectives</h3> In this study, we examined the association of metabolic pathways with effector function activity in human T cells. We further investigated the involvement of the identified metabolic pathways in the pathogenesis of autoimmune diseases using the two representative autoimmune arthritis samples, spondyloarthritis (SpA) and rheumatoid arthritis (RA). <h3>Methods</h3> Metabolism-related cell surface transporters (GLUT1, LAT1, and ASCT2) were examined for their expression levels in CD8 T cells and CD4 T cells from peripheral blood using flow cytometry and Western blotting. Cell survival rate was examined in cultured cells under condition of glucose supply or depletion for 6 days. We comprehensively analyzed the expression of metabolic enzymes in CXCR3+CD8 T cells and CXCR3-CD8 T cells using bulk RNA-seq data. We investigated the effects of metabolic-related transporters on the ability to produce inflammatory cytokines (TNF and IFNγ) using inhibitors. Whole blood samples were freshly obtained from active, treatment-naïve patients with SpA (n=15) and RA (n=25), or healthy controls (HC, n=11) and analyzed by flow cytometry. Phenotype and metabolic enzyme expression of T cells in the synovial fluids of patients were also analyzed employing bulk RNA-seq data. <h3>Results</h3> Among metabolic transporters, GLUT1 was found to be expressed at the protein level specifically on CD8 T cells but not CD4 T cells in human peripheral blood. Functional experiments confirmed that CD8 T cells depended on glucose supply to maintain their cell survival compared to CD4 T cells. Interestingly, exploratory experiments revealed that among CD8 T cells, the viability of CXCR3+CD8 T cells was particularly dependent on glucose supply. In line with that, comprehensive analysis by RNA-seq data revealed that CXCR3+CD8 T cells had enhanced expression of glycolytic enzymes, including <i>GLUT1</i>, compared to CXCR3-CD8 T cells. Validation by flow cytometry also confirmed the elevated GLUT1 level at the protein expression in CXCR3+CD8 T cells than in CXCR3-CD8 T cells. Importantly, CXCR3+CD8 T cells had higher effector function activity than CXCR3-CD8 T cells in producing TNF and IFNγ, which was significantly reduced by inhibiting GLUT1 function or depleting glucose. Of note, GLUT1 expression level in CD8 T cells was significantly higher in SpA compared with RA and HC. In addition, proportion of CXCR3+CD8 T cells in peripheral blood was specifically increased in SpA compared with RA and HC (<i>P</i>&lt;0.0001 and <i>P</i>&lt;0.001, respectively). Furthermore, CXCR3+CD8 T cells in peripheral blood from SpA patients had significantly higher expression of GLUT1 compared to CXCR3-CD8 T cells (<i>P</i>&lt;0.0001). Finally, CD8 T cells in the synovial fluids of SpA patients showed dominant <i>CXCR3</i> expression and higher expression of <i>GLUT1</i> among metabolic enzymes, exhibiting their effector activity. <h3>Conclusion</h3> Our results demonstrate that CXCR3+CD8 T cells exhibit higher effector activity than other CD8 T cell phenotypes, regulated by GLUT1-mediated metabolic reprogramming toward glycolysis. GLUT1-high CXCR3+CD8 T cells may be involved in SpA pathogenesis. <h3>Reference</h3> [1]Nat Rev Immunol. 2020 Jan;20(1):55-70. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.